FIBER CONNECTOR
TYPEs
There are many types of connectors in circulation. Previously, the most popular
connector was the ST type, a bayonet connector, that has shown to be unstable.
These connectors can not get certified anymore. If you come across a ST connec -tor in a local area network, and if the installation is no longer stable, the
connec-tor may very well be the reason for the unstability.
Figure 1
The SC connector is very popular because it can be produced at a low price and because it actually works. The only disadvantage of this connector is the size.
Figure 2
Connector Types
SC connector ST connector
Figure 3
Figure 4
Figure 5
The successor to the SC and ST types is the LC ,or Lucent, connector. It is so
small, that if there is room for one Rj-45 connector, there will be room for two
LC connectors, at the same place. Besides that, it is simple and stable, and it is produced by many manufacturers. The LC connector is available in multi mode (beige), single mode (blue) and furthermore, in a non-reflective design (green).
The use of this connector type is becoming more and more widespread. But
again, the biggest advantage of the LC is the small size. In a 43H rack there is room for 1920 LC connectors. There are some problems, though, with the outgo -ing patchcables, due to the many connectors.
Rack shown with LC connectors. Notice
the patch cables on their way to the
active equipment
The passive section LC connector
The MT-Rj connector was, for some time, predicted to be the FTTD (Fiber To The Desk) connector, having two fibers and being just as small as a Rj45 connector.
But now it is not so popular anymore.
Figure 6
The connector shown on figure 7, the FC-PC connector, was earlier on regarded
as one of the best connectors, but now going out of use.
Figure 7
MT-Rj connector
Within the world of tele communications the E-2000 is being widely used. It is a
high-quality type of connector and among other qualities, it is good at handling
the high power in analog tv installations. E-2000 is born with a protection cap, shielding against the very dangerous laser light.
Figure 10
Pre-polished Connectors
There are many plug types and many connection methods to choose from. If you want to make a small number of terminations only, you may use pre-polished
connectors, that is, connectors ready to use. You do not have to polish with figure-eight-shaped movements, as done in “the old days”.
Figure 11
E-2000
Pre-polished connector from Belden
Figure 12
Figure 13
Figure 14
Pre-polished connector from 3M Pre-polished con-nector from LK Pre-polished connector from FujikaraFigure 15
Figure 16
This is a pigtail, that is, a
connec-tor with 1 meter of fiber attached.
All and ready, needs only a clean-ing. Must be spliced, though, by
means of a splicer. Definitely the cheapest solution, but the invest -ment is big.
Figure 17
According to calculations, you must make appr. 500 connections before it pays to buy a fusion splicer. In other words, if you work with fiber over a couple of years, it may be a good investment to buy a splicer.
Figure 18
You must allways use connectors if a need for reconnecting might arise later on.
There are many types of connectors on the market, but they can all be divided
into three main categories.
Patch cable with break out kit
The second category of connectors includes connectors, pre-polished by
man-ufacturer. Tyco, Belden and LK are examples of manufacturers offering
pre-polished connectors. In addition, you will need a small assembly kit for the mounting of these connectors.
The third and last category is the pig tail choice. A pig tail is a mounted
connec-tor with a piece of fiber attached (the pig tail).
Figure 19
Figure 20
When the mounting method has been chosen, you must decide on a connector type, and there is a huge selection to chose from.
The most widespread of the old types is the SC type (square connectors). The new
type gaining ground is the LC (Lucent connector), that only takes up half the space.
It is important to remember the colour codes.
Beige is used for multi mode installations. Blue is used for single mode installations.
Green is used as code for single mode installations, without reflections, which means that the signal does not tolerate reflections. Commonly used in analog tv
Pre-polished connector, with
tool kit, from LK
It is important never to mix differently coloured connectors.
Figure 21
Figure 22
Beige for multi mode
Blue for single mode (PC/UPC)
Green for single mode reflection free (APC)
Green reflection free connector (APC)
Blue single mode connector (PC/UPC)
3 types of SC connectors
2 types of LC connec -tors
Figure 23
A local area network can be carried out as a FTTD (Fiber To The Desk) installation. The fiber is lead to a wall outlet, and from the outlet it is taken further on to an optical fiber network card. Another way of doing it, is to mount a media converter
and then take the signal to the pc, through a copper cable.
SC
LC
LC and SC
connector
A practical example of dimensioning
In the next chapter we shall look at the dimensioning of a small fiber installation. At first we shall deal with the different elements of the installation, and what it takes to get the installation to work. Next, we will investigate results, obtainable
if the installation is properly carried out.
Let us say our task is to connect two racks in a factory installation, and, let us say there is a distance of 200m between the two racks. If we do a multi mode installation, the maximum speed will be 1Gbit and if we do a single mode, the maximum speed will be 40Gbit. That means, we will have to make two calcula
-tions, one for a single mode installation and one for multi mode. Verizon have been testing the first 100Gbit installations in their backbone system for some time (december 2007).
You must remember, that whether you make a calculation or a dimensioning, it
is about the fiber - and the fiber only. We do not concern ourselves with cables,
installation methods, etc. But of course, these matters must dealt with before the
projekt is carried out in the real world. Both fields of work are equally important,
if one of them fails, the installation will not work.
Which items must be taken into consideration?
Attenuation in the fiber
Attenuation in connectors Attenuation in splicings Surplus for repairs
The wavelength in question Reserves, if necessary Light, emitted by transmitter
